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Java版短网址(ShortUrl)的算法

package com.youngsun.lbt;publicclass ShortUrlGenerator {    publicstaticvoid main(String[] args) {       // 长连接: http://www.young-sun.com    // 新浪解析后的短链接为: http://***/Nvqqem       String sLongUrl = "http://www.young-sun.com" ; // 3BD768E58042156E54626860E241E999       String[] aResult = shortUrl (sLongUrl);       // 打印出结果       for ( int i = 0; i < aResult. length ; i++) {            System. out .println( "The string [" + i + "] is " + aResult[i]);       }     }     publicstatic String[] shortUrl(String url) {       // 可以自定义生成 MD5 加密字符传前的混合 KEY       String key = "libotao" ;       // 要使用生成 URL 的字符       String[] chars = new String[] { "a" , "b" , "c" , "d" , "e" , "f" , "g" , "h" ,              "i" , "j" , "k" , "l" , "m" , "n" , "o" , "p" , "q" , "r" , "s" , "t" ,              "u" , "v" , "w" , "x" , "y" , "z" , "0" , "1" , "2" , "3" , "4" , "5" ,              "6" , "7" , "8" , "9" , "A" , "B" , "C" , "D" , "E" , "F" , "G" , "H" ,              "I" , "J" , "K" , "L" , "M" , "N" , "O" , "P" , "Q" , "R" , "S" , "T" ,              "U" , "V" , "W" , "X" , "Y" , "Z"        };       // 对传入网址进行 MD5 加密       String sMD5EncryptResult = (Encript.md5(key + url));       String hex = sMD5EncryptResult;       String[] resUrl = new String[4];        //得到 4组短链接字符串         for ( int i = 0; i < 4; i++) {           // 把加密字符按照 8 位一组 16 进制与 0x3FFFFFFF 进行位与运算           String sTempSubString = hex.substring(i * 8, i * 8 + 8);           // 这里需要使用 long 型来转换,因为 Inteper .parseInt() 只能处理 31 位 , 首位为符号位 , 如果不用 long ,则会越界           long lHexLong = 0x3FFFFFFF & Long.parseLong (sTempSubString, 16);           String outChars = "" ;           //循环获得每组6位的字符串           for ( int j = 0; j < 6; j++) {             // 把得到的值与 0x0000003D 进行位与运算,取得字符数组 chars 索引        //(具体需要看chars数组的长度   以防下标溢出,注意起点为0)              long index = 0x0000003D & lHexLong;              // 把取得的字符相加              outChars += chars[( int ) index];              // 每次循环按位右移 5 位              lHexLong = lHexLong >> 5;           }           // 把字符串存入对应索引的输出数组           resUrl[i] = outChars;       }       return resUrl;    }}

输出结果:

 

The string [0] is ZBbINb

The string [1] is VBnqMb

The string [2] is Nvqqem

The string [3] is yiQFja

 

Java版短网址(ShortUrl)的算法